A wafer-level camera is a camera having a small footprint that can be utilized in electronic devices having a thin form factor, for example a mobile phone, notebook computer, tablet computer, and the like. Such wafer-level cameras include optics to form an image and an image sensor for sensing the image. To form a high quality image, the optics of the camera module may include several lenses, sometimes separated by spacers, that require precise alignment.
However, a wafer level camera is defined by the method of manufacturing and not by the usage. The wafer-level camera is typically manufactured by stacking and bonding wafers having optical components using alignment and bonding techniques similar to semiconductor manufacturing. For example, a sensor wafer having a number of image sensors arranged in an array or grid pattern may be provided first, possibly with a cover glass layer for protection of the sensor substrate. A spacer wafer may be placed on the image sensor wafer having a number of openings, each aligned with one of the image sensors. A wafer having a number of lenses, known as a lens plate, is then placed on the spacer wafer such that each lens is aligned with one of the image sensors. A second spacer wafer may be provided before a second lens plate having a number of lenses is placed on the wafer stack. In this manner, multiple spacer wafers and multiple lens plates may be included in the manufacturing of wafer-level cameras. Finally, the stacked wafers are bonded and diced into individual wafer-level cameras each having an image sensor and a stack of spacers and lenses.
Such manufacturing techniques can also be implemented using lens plates and spacer wafers without necessarily including the sensor wafer in order to produce an integrated lens stack.